This invention concerns the field of motor vehicle wheel attitude checking in general, and more particularly relates to a self-centering device for supporting the heads or sensors for checking and measuring said attitude.
Said heads and their method of use will not be described, being extraneous to the objects of the invention.
Said heads are associated with the wheel rims of a motor vehicle by using appropriate self-centering devices, a typical example of which is fully described in Italian Model No. 224605 in the name of the same Applicant.
The device of said document comprises four mutually parallel clamps, usually of double acting type, i.e. able to engage the bead retention flange of a wheel rim either from the inside, typically in the case of sheet steel wheel rims, or from the outside, typically in the case of alloy wheel rims.
Said clamps are arranged in a substantially cross arrangement about the centre of a flat frame comprising two parallel side-by-side bars on which two sliders are slidingly mounted.
Each slider supports two clamps, said clamps projecting from the plane in which said two bars lie.
Between the two bars there is a parallel rod which is rotatably mounted on said frame and presents two threaded portions with opposite handed threads on which said two sliders are engaged, so that the respective pairs of clamps can be made to approach or withdraw from each other on the basis of the nominal diameter of the wheel rim.
Said rod is rotated by at least one terminal knob, which is fixed to one of its ends outside the overall contour of the frame.
A projecting pin is also provided for supporting an attitude checking head, the pin being perpendicular to the frame and located on the opposite side of it to that occupied by the clamps.
Said pin lies at the centre of the device, and is preferably aligned with the wheel rim axis.
As explained hereinbefore, to arrange the four clamps on the wheel rim circumference, the distance between the two clamp sliders has to be increased or decreased, this being done by rotating the threaded rod.
As wheel rims of considerably different nominal diameters ranging from 8-10 to 20-22 inches or more are currently available, devices of at least two different sizes must be to hand because the device suitable for the smaller diameters cannot be used for the larger diameters, and vice versa.
In particular, such known devices have proved inconvenient from their overall size aspect, because when performing out-of-plane or off-centre operations or checks on wheel rims typically of relatively small diameter, which operations require the wheel to be rotated on a surface, the device may come into contact with said surface, so preventing such checks from being carried out.
The main object of this invention is to provide a single device which can be associated with the entire range of commercially available wheel rims.
A further object is to provide a self-centering device able to avoid contact with the ground when out-of-plane or off-centre checks are being made, even in the case of relatively small nominal diameter wheel rims.
Another object is to attain the aforesaid objects within the context of a simple, rational, reliable and durable construction.
Said objects are attained by virtue of the characteristics indicated in the claims.
Basically, according to the invention, each clamp is connected to the respective slider by means which enable the distance between the clamp and slider to be varied as required.
By virtue of this provision, all the objects of the invention are attained.
In this respect, to change the self-centering device from that configuration suitable for example for wheel rims of large diameter, for example 22 inches or more, to that suitable for wheel rims of small diameter, for example 8 inches, the clamps have merely to be moved closer to the sliders, and the rod operated through the distance necessary to engage the clamps with the wheel rim.
Moreover, while maintaining the sliders in a determined configuration, for example practically at their maximum distance apart, the position of the devices can be adapted to relatively different wheel rim diameters, for example from 16 to 22 inches.
As will be seen, adjusting the position of the clamps becomes a very simple matter, and by virtue of the said adjustment the device of the invention enables off-centre and out-of-plane operations and checks to be carried out without problems arising, even on very small wheels which at that moment rest on the ground.
The said device is shaped and dimensioned in such a manner as to be able to independently support the attitude checking head or sensor, i.e. without any accessories being required.